3.9.4 Add tests to the transcript crate

crypto/transcript/Cargo.toml

@@ -18,6 +18,10 @@ digest = "0.10"
 blake2 = { version = "0.10", optional = true }
 merlin = { version = "3", optional = true }
 
+[dev-dependencies]
+blake2 = "0.10"
+
 [features]
 recommended = ["blake2"]
 merlin = ["dep:merlin"]
+tests = []

crypto/transcript/src/lib.rs

@@ -6,6 +6,9 @@ mod merlin;
 #[cfg(feature = "merlin")]
 pub use crate::merlin::MerlinTranscript;
 
+#[cfg(any(test, feature = "tests"))]
+pub mod tests;
+
 use digest::{
   typenum::{
     consts::U32, marker_traits::NonZero, type_operators::IsGreaterOrEqual, operator_aliases::GrEq,

crypto/transcript/src/tests.rs

@@ -0,0 +1,95 @@
+use crate::Transcript;
+
+pub fn test_transcript<T: Transcript>()
+where
+  T::Challenge: PartialEq,
+{
+  // Ensure distinct names cause distinct challenges
+  {
+    let mut t1 = T::new(b"1");
+    let mut t2 = T::new(b"2");
+    assert!(t1.challenge(b"c") != t2.challenge(b"c"));
+  }
+
+  // Ensure names can't lead into labels
+  {
+    let mut t1 = T::new(b"12");
+    let c1 = t1.challenge(b"c");
+    let mut t2 = T::new(b"1");
+    let c2 = t2.challenge(b"2c");
+    assert!(c1 != c2);
+  }
+
+  let t = || T::new(b"name");
+  let c = |mut t: T| t.challenge(b"c");
+
+  // Ensure domain separators do something
+  {
+    let mut t1 = t();
+    t1.domain_separate(b"d");
+    assert!(c(t1) != c(t()));
+  }
+
+  // Ensure distinct domain separators create distinct challenges
+  {
+    let mut t1 = t();
+    let mut t2 = t();
+    t1.domain_separate(b"d1");
+    t2.domain_separate(b"d2");
+    assert!(c(t1) != c(t2));
+  }
+
+  // Ensure distinct messages create distinct challenges
+  {
+    // By label
+    {
+      let mut t1 = t();
+      let mut t2 = t();
+      t1.append_message(b"msg", b"a");
+      t2.append_message(b"msg", b"b");
+      assert!(c(t1) != c(t2));
+    }
+
+    // By value
+    {
+      let mut t1 = t();
+      let mut t2 = t();
+      t1.append_message(b"a", b"val");
+      t2.append_message(b"b", b"val");
+      assert!(c(t1) != c(t2));
+    }
+  }
+
+  // Ensure challenges advance the transcript
+  {
+    let mut t = t();
+    let c1 = t.challenge(b"c");
+    let c2 = t.challenge(b"c");
+    assert!(c1 != c2);
+  }
+
+  // Ensure distinct challenge labels produce distinct challenges
+  assert!(t().challenge(b"a") != t().challenge(b"b"));
+
+  // Ensure RNG seed calls advance the transcript
+  {
+    let mut t = t();
+    let s1 = t.rng_seed(b"s");
+    let s2 = t.rng_seed(b"s");
+    assert!(s1 != s2);
+  }
+
+  // Ensure distinct RNG seed labels produce distinct seeds
+  assert!(t().rng_seed(b"a") != t().rng_seed(b"b"));
+}
+
+#[test]
+fn test_digest() {
+  test_transcript::<crate::DigestTranscript<blake2::Blake2b512>>();
+}
+
+#[cfg(feature = "merlin")]
+#[test]
+fn test_merlin() {
+  test_transcript::<crate::MerlinTranscript>();
+}